L. Torri, L. Piergiovanni, E. Caldiroli. Food Additives and Contaminants, 2008, 25(4)?-502.
A study was carried out of the odour properties of polyolefins destined for flexible food packaging. A total of 25 homo- and copolymers of ethylene and five homo- and copolymers of polypropylene in pellet grade were analysed by a sensory panel. Principal component analyses of sensory data showed a perceptible and quantifiable difference between samples. Generally, polypropylene materials were judged less odorous than the majority of polyethylene pellets, especially the ethylene vinyl acetate copolymers. The feasibility of using a commercial electronic nose, equipped with 10 metal oxide semiconductors, to discriminate between the odour of plastic materials was also explored. Instrumental results were satisfactory and correlated well with panel answers, as shown by partial least-squares regression. Furthermore, application of a cluster analysis made it possible to differentiate polymer odours into strong, medium and weak.
S. Pastorelli, L. Torri, S. Valzacchi, A. Rodriguez, S. Limbo, C.Simoneau, 2007. Food Additives and Contaminants, 2007, 24(11)?-1225.
Dry foods with high fat content are susceptible to lipid oxidation, which involves a quality deterioration of the product, since this process is responsible for the generation of off-flavours. Hexanal is considered to be a good shelf-life indicator of such oxidation products. In addition, due to its high volatility, hexanal can be easily determined by fast headspace analytical techniques. For this reason an electronic nose comprising ten metal oxide semiconductors (MOS) and a solid-phase microextraction (SPME) coupled with gas chromatography and flame ionization detector (GC-FID) method were compared in order to determine hexanal formed in hazelnuts during storage under different conditions (room temperature, 40°C, ultraviolet light, with and without oxygen scavenger). The results obtained by the two methods showed a good correlation, confirming the possibility of using a multi-sensor system as a screening tool for the monitoring of shelf-life and oxidation state of nuts.
M. Riva, L. Torri. Shelf Life International Meeting 2008, Ischia, 25-28 giugno 2008
M. Riva, N. Sinelli, L. Torri, S. Limbo. Shelf Life International Meeting 2008, Ischia, 25-28 giugno 2008
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Giuliana D'Imporzano, Fernando Crivelli, Fabrizio Adani, ELSEVIER ScinceDirect, STOTEN-10627 , pag. 7.
Composting is a technique that is used to convert organic waste into agriculturally useful products. Composting is an aerobic, solid-state biological process, which typically can be divided into two phases, a high-rate composting phase and a curing phase. High-rate composting plays an important role during the composting process, owing to the high microbial activity occurring during this phase. It requires an accurate plant design to prevent the formation of anaerobic conditions and odors. The formation of anaerobic conditions mainly depends on the rate of O2 consumption needed to degrade the substrate,i.e., the biological stability of the substrate. In this study, we investigated the relationship between the biological activity, measured by the dynamic respiration index (DRI) and the odor molecules production, measured by an electronic nose (EN) during two food-waste high-rate composting processes. Although the O2 concentration in the biomass free air space (FAS) was kept optimal (O2N140 ml l?1, v/v) during composting, strong anaerobic conditions developed. This was indicated by the high levels of sulfur compounds, methane, and hydrogen in the outlet air stream. Both the high level of O2 consumption, needed to degrade the high-degradable water-soluble organic matter and the low water O2 solubility, caused by high temperature reached in this stage (up to 60 �C), led to the anaerobic conditions observed in the biofilm-particle level. The application of the partial least square (PLS) analysis demonstrated a good regression between the DRI and the odor molecules produced that was detected by the EN (R2=0.991; R2 CV=0.990), signifying the usefulness of the DRI as a parameter to estimate the potential production of odor molecules of the biomass. ................................................................................. ........................This work was designed to evaluate the relationship between the biological ability of a substrate and the odours measured by an electronic nose (EN), produced during a labscale composting process, performed under optimal aeration condition.